Identification of a Homopolymer of 5-Acetamidino-7-acetamido-3,5,7,9-tetradeoxy-D-glycero-D-talo-nonulosonic Acid in the Lipopolysaccharides of Legionella pneumophila Non-1 Serogroups

Y. A. Knirel^1,2*, S. N. Senchenkova¹, N. A. Kocharova¹, A. S. Shashkov¹, J. H. Helbig³, and U. Zähringer²

¹Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 119991 Russia; fax: (095) 135-5328; E-mail: knirel@ioc.ac.ru

²Research Center Borstel, Center for Medicine and Biosciences, Parkallee 22, D-23845 Borstel, Germany; fax: (49-4537) 188612; E-mail: uzaehr@fz-borstel.de

³Institute of Medical Microbiology and Hygiene, University Clinic of the Dresden Technical University, Dürerstraße 24, D-01307 Dresden, Germany; fax: (49-351) 4638573; E-mail: jh22@irz.inf.tu-dresden.de

^* To whom correspondence should be addressed.

Received March 23, 2001

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O-Specific polysaccharides (OPS) were isolated by mild acid hydrolysis of the lipopolysaccharides (LPS) of strains of Legionella pneumophila serogroups 2-14, as well as strains Lansing 3 and 16453-92 from newly proposed serogroups. The OPS were studied by ¹H- and ¹³C-NMR spectroscopy, GLC/mass spectrometry, and chemical modifications (mild alkaline O-deacetylation and conversion of the N-acetimidoyl group into the N-acetyl group). All OPS were found to be a homopolymer of a 5-acetamidino-7-acetamido-3,5,7,9-tetradeoxynonulosonic acid, which in some strains is 8-O-acetylated. In most strains studied, the monosaccharide has the D-glycero-D-talo configuration and is thus the C4 epimer of legionaminic acid (4-epilegionaminic acid), which has been previously identified as the monomer in the OPS of L. pneumophila serogroup 1. Poly(4-epilegionaminic acid) occurs as a minor polysaccharide in serogroups 5 (strain Dallas 1) and 13 and is absent in serogroups 1 and 7. The chemical basis for serological differentiation of L. pneumophila strains is discussed.

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KEY WORDS: lipopolysaccharide, O-specific polysaccharide, structure, 5-acetamidino-7-acetamido-3,5,7,9-tetradeoxy-D-glycero-D-talo-nonulosonic acid, legionaminic acid, Legionella pneumophila

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